1. Field of the Invention
The invention relates to a process and apparatus for applying a nonadhesive insulating tape to the winding of an electric coil, which is used, in particular, as an intermediate, cover or shielding insulation.
2. Description of the Prior Art
Swiss Patent Publication 568,918 discloses an apparatus for applying adhesive tape to the winding of an electric coil wherein a support, capable of being moved between a rest position and a working position, is provided with a pressure shoe for the adhesive tape. On the support, a slide displaceable between two terminal positions is provided. The slide is equipped with means to draw the adhesive tape during its movement into its terminal position in the direction of the pressure shoe. The slide is also equipped with a blade moving on a path transverse to the direction of motion of the slide, between one terminal position of the slide and the pressure shoe.
However, this insulating apparatus permits only the use of one-sided adhesive tape, manufactured specifically for this type of application. Only a limited selection of such adhesive tapes is available, so that the different insulation requirements, such as those related to electrical properties, temperature resistance and the like, cannot always be satisfied.
In a published German Patent, DE 31 39 496, an apparatus for applying sections of a nonadhesive tape to a winding form is disclosed, which, in the case of a multiple spindle winding machine, is integrated with each winding spindle. As the winding time is usually five times the time required for the application of the tape, the tape winding devices are not optimally used, having a utilization factor of about 20%. Furthermore, during the application of the adhesive tape, the winding machine must be inactive so that additional loss of time cannot be avoided. Another disadvantage consists of the fact that both nonadhesive tapes and tapes coated on one side with an adhesive must be rotated around the longitudinal axes by about 90.degree., primarily because space is considerably limited due to the given spacing of the spindles. This may lead to problems, especially in the case of broader tapes, since irregularly warped tapes may be produced by stressing. Thus, the uniform application of the tape to the coil is no longer assured.